JC-1 mitochondrial membrane potential assay kit (Cayman chemical, Ann Arbor, MI) was used for this assay, following the manufacture’s instruction. The cytofluorimetric, lipophilic cationic dye, 5,5′,6,6′-tetrachloro-1,1′3,3-tetracthylbenzimidazolylcarbocyanine idodide (JC-1), can selectively enter into mitochondria and reversibly change color from green to red as the membrane potential increases. AM cells were treated as above and an equal amount of dye was added. After 30-min incubation, fluorescence was measured using a fluorometer, using 560 nm excitation and a 595 nm emission filter for detecting healthy cells, and 485 nm excitation and a 535 nm emission filter for detecting dead cells (35 (link)).